<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>simple</title>
    </head>
    <body>
        <div class="father">
            <div class="son a"></div>
            <div class="son b"></div>
            <div class="son c"></div>
        </div>
        <style>
            /* 优先父控子 */
            .father{
                width: 600px;
                height: 100px;
                background-color: azure;
                /* 1开启flex布局 */
                display: flex;
                /* 2确定主轴方向 row 是默认值 */
                flex-direction: row;
                /* 3父标签 整体调控子标签在主轴方向上的排列 */
                justify-content: start;
                /* 4交叉轴 垂直于主轴 默认stretch */
                align-items: stretch;
            }
            .son{
                margin: 2px;
                background-color: rebeccapurple;
            }
            .a{
                width: 40px;
                /* height: 40px; */
            }
            .b{
                width: 50px;
                /* height: 50px; */
                flex:1;
                background-color: rgb(17, 26, 23);
            }
            .c{
                width: 60px;
                /* height: 60px; */
                background-color: burlywood;
                flex: 2;
            }
        </style>
    </body>
</html>